dygraph-range-selector.js

   1 /*
   2  * @license
   3  * Copyright 2011 Paul Felix (paul.eric.felix@gmail.com)
   4  * MIT-licensed (http://opensource.org/licenses/MIT)
   5  */
   6
   7 /**
   8  * @fileoverview This file contains the DygraphRangeSelector class used to provide
   9  * a timeline range selector widget for dygraphs.
  10  */
  11
  12 /*jshint globalstrict: true */
  13 /*global Dygraph:false */
  14 "use strict";
  15
  16 /**
  17  * The DygraphRangeSelector class provides a timeline range selector widget.
  18  * @param {Dygraph} dygraph The dygraph object
  19  * @constructor
  20  */
  21 var DygraphRangeSelector = function(dygraph) {
  22   this.isIE_ = /MSIE/.test(navigator.userAgent) && !window.opera;
  23   this.isUsingExcanvas_ = dygraph.isUsingExcanvas_;
  24   this.dygraph_ = dygraph;
  25   this.hasTouchInterface_ = typeof(TouchEvent) != 'undefined';
  26   this.isMobileDevice_ = /mobile|android/gi.test(navigator.appVersion);
  27   this.createCanvases_();
  28   if (this.isUsingExcanvas_) {
  29     this.createIEPanOverlay_();
  30   }
  31   this.createZoomHandles_();
  32   this.initInteraction_();
  33 };
  34
  35 /**
  36  * Adds the range selector to the dygraph.
  37  * @param {Object} graphDiv The container div for the range selector.
  38  * @param {DygraphLayout} layout The DygraphLayout object for this graph.
  39  */
  40 DygraphRangeSelector.prototype.addToGraph = function(graphDiv, layout) {
  41   this.layout_ = layout;
  42   this.resize_();
  43   graphDiv.appendChild(this.bgcanvas_);
  44   graphDiv.appendChild(this.fgcanvas_);
  45   graphDiv.appendChild(this.leftZoomHandle_);
  46   graphDiv.appendChild(this.rightZoomHandle_);
  47 };
  48
  49 /**
  50  * Renders the static background portion of the range selector.
  51  */
  52 DygraphRangeSelector.prototype.renderStaticLayer = function() {
  53   this.resize_();
  54   this.drawStaticLayer_();
  55 };
  56
  57 /**
  58  * Renders the interactive foreground portion of the range selector.
  59  */
  60 DygraphRangeSelector.prototype.renderInteractiveLayer = function() {
  61   if (this.isChangingRange_) {
  62     return;
  63   }
  64   this.placeZoomHandles_();
  65   this.drawInteractiveLayer_();
  66 };
  67
  68 /**
  69  * @private
  70  * Resizes the range selector.
  71  */
  72 DygraphRangeSelector.prototype.resize_ = function() {
  73   function setElementRect(canvas, rect) {
  74     canvas.style.top = rect.y + 'px';
  75     canvas.style.left = rect.x + 'px';
  76     canvas.width = rect.w;
  77     canvas.height = rect.h;
  78     canvas.style.width = canvas.width + 'px';    // for IE
  79     canvas.style.height = canvas.height + 'px';  // for IE
  80   }
  81
  82   var plotArea = this.layout_.getPlotArea();
  83   var xAxisLabelHeight = this.attr_('xAxisHeight') || (this.attr_('axisLabelFontSize') + 2 * this.attr_('axisTickSize'));
  84   this.canvasRect_ = {
  85     x: plotArea.x,
  86     y: plotArea.y + plotArea.h + xAxisLabelHeight + 4,
  87     w: plotArea.w,
  88     h: this.attr_('rangeSelectorHeight')
  89   };
  90
  91   setElementRect(this.bgcanvas_, this.canvasRect_);
  92   setElementRect(this.fgcanvas_, this.canvasRect_);
  93 };
  94
  95 DygraphRangeSelector.prototype.attr_ = function(name) {
  96   return this.dygraph_.attr_(name);
  97 };
  98
  99 /**
 100  * @private
 101  * Creates the background and foreground canvases.
 102  */
 103 DygraphRangeSelector.prototype.createCanvases_ = function() {
 104   this.bgcanvas_ = Dygraph.createCanvas();
 105   this.bgcanvas_.className = 'dygraph-rangesel-bgcanvas';
 106   this.bgcanvas_.style.position = 'absolute';
 107   this.bgcanvas_.style.zIndex = 9;
 108   this.bgcanvas_ctx_ = Dygraph.getContext(this.bgcanvas_);
 109
 110   this.fgcanvas_ = Dygraph.createCanvas();
 111   this.fgcanvas_.className = 'dygraph-rangesel-fgcanvas';
 112   this.fgcanvas_.style.position = 'absolute';
 113   this.fgcanvas_.style.zIndex = 9;
 114   this.fgcanvas_.style.cursor = 'default';
 115   this.fgcanvas_ctx_ = Dygraph.getContext(this.fgcanvas_);
 116 };
 117
 118 /**
 119  * @private
 120  * Creates overlay divs for IE/Excanvas so that mouse events are handled properly.
 121  */
 122 DygraphRangeSelector.prototype.createIEPanOverlay_ = function() {
 123   this.iePanOverlay_ = document.createElement("div");
 124   this.iePanOverlay_.style.position = 'absolute';
 125   this.iePanOverlay_.style.backgroundColor = 'white';
 126   this.iePanOverlay_.style.filter = 'alpha(opacity=0)';
 127   this.iePanOverlay_.style.display = 'none';
 128   this.iePanOverlay_.style.cursor = 'move';
 129   this.fgcanvas_.appendChild(this.iePanOverlay_);
 130 };
 131
 132 /**
 133  * @private
 134  * Creates the zoom handle elements.
 135  */
 136 DygraphRangeSelector.prototype.createZoomHandles_ = function() {
 137   var img = new Image();
 138   img.className = 'dygraph-rangesel-zoomhandle';
 139   img.style.position = 'absolute';
 140   img.style.zIndex = 10;
 141   img.style.visibility = 'hidden'; // Initially hidden so they don't show up in the wrong place.
 142   img.style.cursor = 'col-resize';
 143
 144   if (/MSIE 7/.test(navigator.userAgent)) { // IE7 doesn't support embedded src data.
 145     img.width = 7;
 146     img.height = 14;
 147     img.style.backgroundColor = 'white';
 148     img.style.border = '1px solid #333333'; // Just show box in IE7.
 149   } else {
 150     img.width = 9;
 151     img.height = 16;
 152     img.src = 'data:image/png;base64,' +
 153 'iVBORw0KGgoAAAANSUhEUgAAAAkAAAAQCAYAAADESFVDAAAAAXNSR0IArs4c6QAAAAZiS0dEANAA' +
 154 'zwDP4Z7KegAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAAd0SU1FB9sHGw0cMqdt1UwAAAAZdEVYdENv' +
 155 'bW1lbnQAQ3JlYXRlZCB3aXRoIEdJTVBXgQ4XAAAAaElEQVQoz+3SsRFAQBCF4Z9WJM8KCDVwownl' +
 156 '6YXsTmCUsyKGkZzcl7zkz3YLkypgAnreFmDEpHkIwVOMfpdi9CEEN2nGpFdwD03yEqDtOgCaun7s' +
 157 'qSTDH32I1pQA2Pb9sZecAxc5r3IAb21d6878xsAAAAAASUVORK5CYII=';
 158   }
 159
 160   if (this.isMobileDevice_) {
 161     img.width *= 2;
 162     img.height *= 2;
 163   }
 164
 165   this.leftZoomHandle_ = img;
 166   this.rightZoomHandle_ = img.cloneNode(false);
 167 };
 168
 169 /**
 170  * @private
 171  * Sets up the interaction for the range selector.
 172  */
 173 DygraphRangeSelector.prototype.initInteraction_ = function() {
 174   var self = this;
 175   var topElem = this.isIE_ ? document : window;
 176   var xLast = 0;
 177   var handle = null;
 178   var isZooming = false;
 179   var isPanning = false;
 180   var dynamic = !this.isMobileDevice_ && !this.isUsingExcanvas_;
 181
 182   // We cover iframes during mouse interactions. See comments in
 183   // dygraph-utils.js for more info on why this is a good idea.
 184   var tarp = new Dygraph.IFrameTarp();
 185
 186   // functions, defined below.  Defining them this way (rather than with
 187   // "function foo() {...}" makes JSHint happy.
 188   var toXDataWindow, onZoomStart, onZoom, onZoomEnd, doZoom, isMouseInPanZone,
 189       onPanStart, onPan, onPanEnd, doPan, onCanvasMouseMove, applyBrowserZoomLevel;
 190
 191   // Touch event functions
 192   var onZoomHandleTouchEvent, onCanvasTouchEvent, addTouchEvents;
 193
 194   toXDataWindow = function(zoomHandleStatus) {
 195     var xDataLimits = self.dygraph_.xAxisExtremes();
 196     var fact = (xDataLimits[1] - xDataLimits[0])/self.canvasRect_.w;
 197     var xDataMin = xDataLimits[0] + (zoomHandleStatus.leftHandlePos - self.canvasRect_.x)*fact;
 198     var xDataMax = xDataLimits[0] + (zoomHandleStatus.rightHandlePos - self.canvasRect_.x)*fact;
 199     return [xDataMin, xDataMax];
 200   };
 201
 202   applyBrowserZoomLevel = function(delX) {
 203     var zoom = window.outerWidth/document.documentElement.clientWidth;
 204     if (!isNaN(zoom)) {
 205       return delX/zoom;
 206     } else {
 207       return delX;
 208     }
 209   };
 210
 211   onZoomStart = function(e) {
 212     Dygraph.cancelEvent(e);
 213     isZooming = true;
 214     xLast = e.screenX;
 215     handle = e.target ? e.target : e.srcElement;
 216     self.dygraph_.addEvent(topElem, 'mousemove', onZoom);
 217     self.dygraph_.addEvent(topElem, 'mouseup', onZoomEnd);
 218     self.fgcanvas_.style.cursor = 'col-resize';
 219     tarp.cover();
 220     return true;
 221   };
 222
 223   onZoom = function(e) {
 224     if (!isZooming) {
 225       return false;
 226     }
 227     Dygraph.cancelEvent(e);
 228     var delX = e.screenX - xLast;
 229     if (Math.abs(delX) < 4 || e.screenX === 0) {
 230       // First iPad move event seems to have screenX = 0
 231       return true;
 232     }
 233     xLast = e.screenX;
 234     delX = applyBrowserZoomLevel(delX);
 235
 236     // Move handle.
 237     var zoomHandleStatus = self.getZoomHandleStatus_();
 238     var newPos;
 239     if (handle == self.leftZoomHandle_) {
 240       newPos = zoomHandleStatus.leftHandlePos + delX;
 241       newPos = Math.min(newPos, zoomHandleStatus.rightHandlePos - handle.width - 3);
 242       newPos = Math.max(newPos, self.canvasRect_.x);
 243     } else {
 244       newPos = zoomHandleStatus.rightHandlePos + delX;
 245       newPos = Math.min(newPos, self.canvasRect_.x + self.canvasRect_.w);
 246       newPos = Math.max(newPos, zoomHandleStatus.leftHandlePos + handle.width + 3);
 247     }
 248     var halfHandleWidth = handle.width/2;
 249     handle.style.left = (newPos - halfHandleWidth) + 'px';
 250     self.drawInteractiveLayer_();
 251
 252     // Zoom on the fly (if not using excanvas).
 253     if (dynamic) {
 254       doZoom();
 255     }
 256     return true;
 257   };
 258
 259   onZoomEnd = function(e) {
 260     if (!isZooming) {
 261       return false;
 262     }
 263     isZooming = false;
 264     tarp.uncover();
 265     Dygraph.removeEvent(topElem, 'mousemove', onZoom);
 266     Dygraph.removeEvent(topElem, 'mouseup', onZoomEnd);
 267     self.fgcanvas_.style.cursor = 'default';
 268
 269     // If using excanvas, Zoom now.
 270     if (!dynamic) {
 271       doZoom();
 272     }
 273     return true;
 274   };
 275
 276   doZoom = function() {
 277     try {
 278       var zoomHandleStatus = self.getZoomHandleStatus_();
 279       self.isChangingRange_ = true;
 280       if (!zoomHandleStatus.isZoomed) {
 281         self.dygraph_.doUnzoom_();
 282       } else {
 283         var xDataWindow = toXDataWindow(zoomHandleStatus);
 284         self.dygraph_.doZoomXDates_(xDataWindow[0], xDataWindow[1]);
 285       }
 286     } finally {
 287       self.isChangingRange_ = false;
 288     }
 289   };
 290
 291   isMouseInPanZone = function(e) {
 292     if (self.isUsingExcanvas_) {
 293         return e.srcElement == self.iePanOverlay_;
 294     } else {
 295       var rect = self.leftZoomHandle_.getBoundingClientRect();
 296       var leftHandleClientX = rect.left + rect.width/2;
 297       rect = self.rightZoomHandle_.getBoundingClientRect();
 298       var rightHandleClientX = rect.left + rect.width/2;
 299       return (e.clientX > leftHandleClientX && e.clientX < rightHandleClientX);
 300     }
 301   };
 302
 303   onPanStart = function(e) {
 304     if (!isPanning && isMouseInPanZone(e) && self.getZoomHandleStatus_().isZoomed) {
 305       Dygraph.cancelEvent(e);
 306       isPanning = true;
 307       xLast = e.screenX;
 308       self.dygraph_.addEvent(topElem, 'mousemove', onPan);
 309       self.dygraph_.addEvent(topElem, 'mouseup', onPanEnd);
 310       return true;
 311     }
 312     return false;
 313   };
 314
 315   onPan = function(e) {
 316     if (!isPanning) {
 317       return false;
 318     }
 319     Dygraph.cancelEvent(e);
 320
 321     var delX = e.screenX - xLast;
 322     if (Math.abs(delX) < 4) {
 323       return true;
 324     }
 325     xLast = e.screenX;
 326     delX = applyBrowserZoomLevel(delX);
 327
 328     // Move range view
 329     var zoomHandleStatus = self.getZoomHandleStatus_();
 330     var leftHandlePos = zoomHandleStatus.leftHandlePos;
 331     var rightHandlePos = zoomHandleStatus.rightHandlePos;
 332     var rangeSize = rightHandlePos - leftHandlePos;
 333     if (leftHandlePos + delX <= self.canvasRect_.x) {
 334       leftHandlePos = self.canvasRect_.x;
 335       rightHandlePos = leftHandlePos + rangeSize;
 336     } else if (rightHandlePos + delX >= self.canvasRect_.x + self.canvasRect_.w) {
 337       rightHandlePos = self.canvasRect_.x + self.canvasRect_.w;
 338       leftHandlePos = rightHandlePos - rangeSize;
 339     } else {
 340       leftHandlePos += delX;
 341       rightHandlePos += delX;
 342     }
 343     var halfHandleWidth = self.leftZoomHandle_.width/2;
 344     self.leftZoomHandle_.style.left = (leftHandlePos - halfHandleWidth) + 'px';
 345     self.rightZoomHandle_.style.left = (rightHandlePos - halfHandleWidth) + 'px';
 346     self.drawInteractiveLayer_();
 347
 348     // Do pan on the fly (if not using excanvas).
 349     if (dynamic) {
 350       doPan();
 351     }
 352     return true;
 353   };
 354
 355   onPanEnd = function(e) {
 356     if (!isPanning) {
 357       return false;
 358     }
 359     isPanning = false;
 360     Dygraph.removeEvent(topElem, 'mousemove', onPan);
 361     Dygraph.removeEvent(topElem, 'mouseup', onPanEnd);
 362     // If using excanvas, do pan now.
 363     if (!dynamic) {
 364       doPan();
 365     }
 366     return true;
 367   };
 368
 369   doPan = function() {
 370     try {
 371       self.isChangingRange_ = true;
 372       self.dygraph_.dateWindow_ = toXDataWindow(self.getZoomHandleStatus_());
 373       self.dygraph_.drawGraph_(false);
 374     } finally {
 375       self.isChangingRange_ = false;
 376     }
 377   };
 378
 379   onCanvasMouseMove = function(e) {
 380     if (isZooming || isPanning) {
 381       return;
 382     }
 383     var cursor = isMouseInPanZone(e) ? 'move' : 'default';
 384     if (cursor != self.fgcanvas_.style.cursor) {
 385       self.fgcanvas_.style.cursor = cursor;
 386     }
 387   };
 388
 389   onZoomHandleTouchEvent = function(e) {
 390     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 391       if (onZoomStart(e.targetTouches[0])) {
 392         Dygraph.cancelEvent(e);
 393       }
 394     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 395       if (onZoom(e.targetTouches[0])) {
 396         Dygraph.cancelEvent(e);
 397       }
 398     } else {
 399       onZoomEnd(e);
 400     }
 401   };
 402
 403   onCanvasTouchEvent = function(e) {
 404     if (e.type == 'touchstart' && e.targetTouches.length == 1) {
 405       if (onPanStart(e.targetTouches[0])) {
 406         Dygraph.cancelEvent(e);
 407       }
 408     } else if (e.type == 'touchmove' && e.targetTouches.length == 1) {
 409       if (onPan(e.targetTouches[0])) {
 410         Dygraph.cancelEvent(e);
 411       }
 412     } else {
 413       onPanEnd(e);
 414     }
 415   };
 416
 417   addTouchEvents = function(elem, fn) {
 418     var types = ['touchstart', 'touchend', 'touchmove', 'touchcancel'];
 419     for (var i = 0; i < types.length; i++) {
 420       self.dygraph_.addEvent(elem, types[i], fn);
 421     }
 422   };
 423
 424   this.dygraph_.attrs_.interactionModel =
 425       Dygraph.Interaction.dragIsPanInteractionModel;
 426   this.dygraph_.attrs_.panEdgeFraction = 0.0001;
 427
 428   var dragStartEvent = window.opera ? 'mousedown' : 'dragstart';
 429   this.dygraph_.addEvent(this.leftZoomHandle_, dragStartEvent, onZoomStart);
 430   this.dygraph_.addEvent(this.rightZoomHandle_, dragStartEvent, onZoomStart);
 431
 432   if (this.isUsingExcanvas_) {
 433     this.dygraph_.addEvent(this.iePanOverlay_, 'mousedown', onPanStart);
 434   } else {
 435     this.dygraph_.addEvent(this.fgcanvas_, 'mousedown', onPanStart);
 436     this.dygraph_.addEvent(this.fgcanvas_, 'mousemove', onCanvasMouseMove);
 437   }
 438
 439   // Touch events
 440   if (this.hasTouchInterface_) {
 441     addTouchEvents(this.leftZoomHandle_, onZoomHandleTouchEvent);
 442     addTouchEvents(this.rightZoomHandle_, onZoomHandleTouchEvent);
 443     addTouchEvents(this.fgcanvas_, onCanvasTouchEvent);
 444   }
 445 };
 446
 447 /**
 448  * @private
 449  * Draws the static layer in the background canvas.
 450  */
 451 DygraphRangeSelector.prototype.drawStaticLayer_ = function() {
 452   var ctx = this.bgcanvas_ctx_;
 453   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 454   try {
 455     this.drawMiniPlot_();
 456   } catch(ex) {
 457     Dygraph.warn(ex);
 458   }
 459
 460   var margin = 0.5;
 461   this.bgcanvas_ctx_.lineWidth = 1;
 462   ctx.strokeStyle = 'gray';
 463   ctx.beginPath();
 464   ctx.moveTo(margin, margin);
 465   ctx.lineTo(margin, this.canvasRect_.h-margin);
 466   ctx.lineTo(this.canvasRect_.w-margin, this.canvasRect_.h-margin);
 467   ctx.lineTo(this.canvasRect_.w-margin, margin);
 468   ctx.stroke();
 469 };
 470
 471
 472 /**
 473  * @private
 474  * Draws the mini plot in the background canvas.
 475  */
 476 DygraphRangeSelector.prototype.drawMiniPlot_ = function() {
 477   var fillStyle = this.attr_('rangeSelectorPlotFillColor');
 478   var strokeStyle = this.attr_('rangeSelectorPlotStrokeColor');
 479   if (!fillStyle && !strokeStyle) {
 480     return;
 481   }
 482
 483   var combinedSeriesData = this.computeCombinedSeriesAndLimits_();
 484   var yRange = combinedSeriesData.yMax - combinedSeriesData.yMin;
 485
 486   // Draw the mini plot.
 487   var ctx = this.bgcanvas_ctx_;
 488   var margin = 0.5;
 489
 490   var xExtremes = this.dygraph_.xAxisExtremes();
 491   var xRange = Math.max(xExtremes[1] - xExtremes[0], 1.e-30);
 492   var xFact = (this.canvasRect_.w - margin)/xRange;
 493   var yFact = (this.canvasRect_.h - margin)/yRange;
 494   var canvasWidth = this.canvasRect_.w - margin;
 495   var canvasHeight = this.canvasRect_.h - margin;
 496
 497   ctx.beginPath();
 498   ctx.moveTo(margin, canvasHeight);
 499   for (var i = 0; i < combinedSeriesData.data.length; i++) {
 500     var dataPoint = combinedSeriesData.data[i];
 501     var x = (dataPoint[0] - xExtremes[0])*xFact;
 502     var y = canvasHeight - (dataPoint[1] - combinedSeriesData.yMin)*yFact;
 503     if (isFinite(x) && isFinite(y)) {
 504       ctx.lineTo(x, y);
 505     }
 506   }
 507   ctx.lineTo(canvasWidth, canvasHeight);
 508   ctx.closePath();
 509
 510   if (fillStyle) {
 511     var lingrad = this.bgcanvas_ctx_.createLinearGradient(0, 0, 0, canvasHeight);
 512     lingrad.addColorStop(0, 'white');
 513     lingrad.addColorStop(1, fillStyle);
 514     this.bgcanvas_ctx_.fillStyle = lingrad;
 515     ctx.fill();
 516   }
 517
 518   if (strokeStyle) {
 519     this.bgcanvas_ctx_.strokeStyle = strokeStyle;
 520     this.bgcanvas_ctx_.lineWidth = 1.5;
 521     ctx.stroke();
 522   }
 523 };
 524
 525 /**
 526  * @private
 527  * Computes and returns the combinded series data along with min/max for the mini plot.
 528  * @return {Object} An object containing combinded series array, ymin, ymax.
 529  */
 530 DygraphRangeSelector.prototype.computeCombinedSeriesAndLimits_ = function() {
 531   var data = this.dygraph_.rawData_;
 532   var logscale = this.attr_('logscale');
 533
 534   // Create a combined series (average of all series values).
 535   var combinedSeries = [];
 536   var sum;
 537   var count;
 538   var mutipleValues;
 539   var i, j, k;
 540   var xVal, yVal;
 541
 542   // Find out if data has multiple values per datapoint.
 543   // Go to first data point that actually has values (see http://code.google.com/p/dygraphs/issues/detail?id=246)
 544   for (i = 0; i < data.length; i++) {
 545     if (data[i].length > 1 && data[i][1] !== null) {
 546       mutipleValues = typeof data[i][1] != 'number';
 547       if (mutipleValues) {
 548         sum = [];
 549         count = [];
 550         for (k = 0; k < data[i][1].length; k++) {
 551           sum.push(0);
 552           count.push(0);
 553         }
 554       }
 555       break;
 556     }
 557   }
 558
 559   for (i = 0; i < data.length; i++) {
 560     var dataPoint = data[i];
 561     xVal = dataPoint[0];
 562
 563     if (mutipleValues) {
 564       for (k = 0; k < sum.length; k++) {
 565         sum[k] = count[k] = 0;
 566       }
 567     } else {
 568       sum = count = 0;
 569     }
 570
 571     for (j = 1; j < dataPoint.length; j++) {
 572       if (this.dygraph_.visibility()[j-1]) {
 573         var y;
 574         if (mutipleValues) {
 575           for (k = 0; k < sum.length; k++) {
 576             y = dataPoint[j][k];
 577             if (y === null || isNaN(y)) continue;
 578             sum[k] += y;
 579             count[k]++;
 580           }
 581         } else {
 582           y = dataPoint[j];
 583           if (y === null || isNaN(y)) continue;
 584           sum += y;
 585           count++;
 586         }
 587       }
 588     }
 589
 590     if (mutipleValues) {
 591       for (k = 0; k < sum.length; k++) {
 592         sum[k] /= count[k];
 593       }
 594       yVal = sum.slice(0);
 595     } else {
 596       yVal = sum/count;
 597     }
 598
 599     combinedSeries.push([xVal, yVal]);
 600   }
 601
 602   // Account for roll period, fractions.
 603   combinedSeries = this.dygraph_.rollingAverage(combinedSeries, this.dygraph_.rollPeriod_);
 604
 605   if (typeof combinedSeries[0][1] != 'number') {
 606     for (i = 0; i < combinedSeries.length; i++) {
 607       yVal = combinedSeries[i][1];
 608       combinedSeries[i][1] = yVal[0];
 609     }
 610   }
 611
 612   // Compute the y range.
 613   var yMin = Number.MAX_VALUE;
 614   var yMax = -Number.MAX_VALUE;
 615   for (i = 0; i < combinedSeries.length; i++) {
 616     yVal = combinedSeries[i][1];
 617     if (yVal !== null && isFinite(yVal) && (!logscale || yVal > 0)) {
 618       yMin = Math.min(yMin, yVal);
 619       yMax = Math.max(yMax, yVal);
 620     }
 621   }
 622
 623   // Convert Y data to log scale if needed.
 624   // Also, expand the Y range to compress the mini plot a little.
 625   var extraPercent = 0.25;
 626   if (logscale) {
 627     yMax = Dygraph.log10(yMax);
 628     yMax += yMax*extraPercent;
 629     yMin = Dygraph.log10(yMin);
 630     for (i = 0; i < combinedSeries.length; i++) {
 631       combinedSeries[i][1] = Dygraph.log10(combinedSeries[i][1]);
 632     }
 633   } else {
 634     var yExtra;
 635     var yRange = yMax - yMin;
 636     if (yRange <= Number.MIN_VALUE) {
 637       yExtra = yMax*extraPercent;
 638     } else {
 639       yExtra = yRange*extraPercent;
 640     }
 641     yMax += yExtra;
 642     yMin -= yExtra;
 643   }
 644
 645   return {data: combinedSeries, yMin: yMin, yMax: yMax};
 646 };
 647
 648 /**
 649  * @private
 650  * Places the zoom handles in the proper position based on the current X data window.
 651  */
 652 DygraphRangeSelector.prototype.placeZoomHandles_ = function() {
 653   var xExtremes = this.dygraph_.xAxisExtremes();
 654   var xWindowLimits = this.dygraph_.xAxisRange();
 655   var xRange = xExtremes[1] - xExtremes[0];
 656   var leftPercent = Math.max(0, (xWindowLimits[0] - xExtremes[0])/xRange);
 657   var rightPercent = Math.max(0, (xExtremes[1] - xWindowLimits[1])/xRange);
 658   var leftCoord = this.canvasRect_.x + this.canvasRect_.w*leftPercent;
 659   var rightCoord = this.canvasRect_.x + this.canvasRect_.w*(1 - rightPercent);
 660   var handleTop = Math.max(this.canvasRect_.y, this.canvasRect_.y + (this.canvasRect_.h - this.leftZoomHandle_.height)/2);
 661   var halfHandleWidth = this.leftZoomHandle_.width/2;
 662   this.leftZoomHandle_.style.left = (leftCoord - halfHandleWidth) + 'px';
 663   this.leftZoomHandle_.style.top = handleTop + 'px';
 664   this.rightZoomHandle_.style.left = (rightCoord - halfHandleWidth) + 'px';
 665   this.rightZoomHandle_.style.top = this.leftZoomHandle_.style.top;
 666
 667   this.leftZoomHandle_.style.visibility = 'visible';
 668   this.rightZoomHandle_.style.visibility = 'visible';
 669 };
 670
 671 /**
 672  * @private
 673  * Draws the interactive layer in the foreground canvas.
 674  */
 675 DygraphRangeSelector.prototype.drawInteractiveLayer_ = function() {
 676   var ctx = this.fgcanvas_ctx_;
 677   ctx.clearRect(0, 0, this.canvasRect_.w, this.canvasRect_.h);
 678   var margin = 1;
 679   var width = this.canvasRect_.w - margin;
 680   var height = this.canvasRect_.h - margin;
 681   var zoomHandleStatus = this.getZoomHandleStatus_();
 682
 683   ctx.strokeStyle = 'black';
 684   if (!zoomHandleStatus.isZoomed) {
 685     ctx.beginPath();
 686     ctx.moveTo(margin, margin);
 687     ctx.lineTo(margin, height);
 688     ctx.lineTo(width, height);
 689     ctx.lineTo(width, margin);
 690     ctx.stroke();
 691     if (this.iePanOverlay_) {
 692       this.iePanOverlay_.style.display = 'none';
 693     }
 694   } else {
 695     var leftHandleCanvasPos = Math.max(margin, zoomHandleStatus.leftHandlePos - this.canvasRect_.x);
 696     var rightHandleCanvasPos = Math.min(width, zoomHandleStatus.rightHandlePos - this.canvasRect_.x);
 697
 698     ctx.fillStyle = 'rgba(240, 240, 240, 0.6)';
 699     ctx.fillRect(0, 0, leftHandleCanvasPos, this.canvasRect_.h);
 700     ctx.fillRect(rightHandleCanvasPos, 0, this.canvasRect_.w - rightHandleCanvasPos, this.canvasRect_.h);
 701
 702     ctx.beginPath();
 703     ctx.moveTo(margin, margin);
 704     ctx.lineTo(leftHandleCanvasPos, margin);
 705     ctx.lineTo(leftHandleCanvasPos, height);
 706     ctx.lineTo(rightHandleCanvasPos, height);
 707     ctx.lineTo(rightHandleCanvasPos, margin);
 708     ctx.lineTo(width, margin);
 709     ctx.stroke();
 710
 711     if (this.isUsingExcanvas_) {
 712       this.iePanOverlay_.style.width = (rightHandleCanvasPos - leftHandleCanvasPos) + 'px';
 713       this.iePanOverlay_.style.left = leftHandleCanvasPos + 'px';
 714       this.iePanOverlay_.style.height = height + 'px';
 715       this.iePanOverlay_.style.display = 'inline';
 716     }
 717   }
 718 };
 719
 720 /**
 721  * @private
 722  * Returns the current zoom handle position information.
 723  * @return {Object} The zoom handle status.
 724  */
 725 DygraphRangeSelector.prototype.getZoomHandleStatus_ = function() {
 726   var halfHandleWidth = this.leftZoomHandle_.width/2;
 727   var leftHandlePos = parseInt(this.leftZoomHandle_.style.left, 10) + halfHandleWidth;
 728   var rightHandlePos = parseInt(this.rightZoomHandle_.style.left, 10) + halfHandleWidth;
 729   return {
 730       leftHandlePos: leftHandlePos,
 731       rightHandlePos: rightHandlePos,
 732       isZoomed: (leftHandlePos - 1 > this.canvasRect_.x || rightHandlePos + 1 < this.canvasRect_.x+this.canvasRect_.w)
 733   };
 734 };